Computing devices, such as personal computers, tablet computers, mobile phones, or other devices, often request content from other computing devices over a network. In a common application, the computing device operated by a requesting user is referred to as the client, and the computing device or system operated by the content provider that responds to the request is the server. A client and server may communicate over an intranet, the Internet, or any other communication network. Clients receive and process content (e.g., web pages) from content servers, either directly or through intermediary systems, such as proxy servers.
Users of client devices often wish to access web pages and other content items that are new and/or popular. For example, users may use search engines, news sites, and the like to access content of interest. However, traditional search engines typically provide results based on relevance, embedded links, or some “ranking” or “score” that may or may not factor in popularity or timeliness. As an alternative to using search engines, users may access various services that provide a more targeted listing of content that is popular. Such services may determine the popularity levels of particular web sites, web pages, search terms, and topics using various sources of behavioral data, such as search engine traffic, blog posts, social network activity, and the like.